1. Field of the Invention
The present invention generally relates to a silencing device. More specifically, the present invention relates to a silencing device that reduces the noise of a fan provided in copying machines and the like.
2. Background Information
Fans are provided in electronic equipment such as copiers, televisions, and personal computers, to discharge the air within the device to the outside of the device to reduce the temperature within the device. Referring to FIG. 13, this type of device includes louvers 101 or the like to change the direction of the wind so that the wind from the fan 100 is not directly discharged outside the device, as shown in FIG. 13.
In this type of device sound is generated by the fan 100 cutting through the air, and the sound leaks are transmitted by device. Depending on the user, this cutting noise of the fan 100 can be perceived as uncomfortable.
A device to reduce this type of noise from a fan is disclosed in for example Japanese Patent Application Laid-open No. H5-73072.
In the device disclosed in this publication, a sound with phase inversion is generated in a separately provided speaker, to reduce the sound of a motor-driven fan for dissipating heat installed in part of a television image receiver. However, as disclosed in the publication, the control method for the active controls to generate the sound with phase inversion is complex. Also, it is necessary to provide a separate speaker and so on, so the number of components increases, which increases the cost.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved silencing device. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.